The present invention relates to apparatus for manipulating stacks of overlapping sheets consisting of paper, cardboard, metallic foil, plastic foil or a combination of these. More particularly, the invention relates to improvements in apparatus for introducing or inserting stacks of sheets into receptacles, for example, into prefabricated cartons consisting of cardboard, wood, sheet metal or other suitable material. Still more particularly, the invention relates to improvements in apparatus wherein the means for inserting piles or stacks into receptacles includes a conveyor at least a portion of which is movable into the interior of an empty receptacle while it supports a stack of paper sheets or the like.
Heretofore known apparatus of the above outlined character normally serve for introduction of stacks of paper sheets or the like into receptacles of the type wherein three side walls extend upwardly from the bottom wall or panel and the fourth side wall is held in a horizontal or in a downwardly inclined position so as to provide a lateral opening for introduction of a stack into the interior of such receptacle. Reference may be had to the aforementioned commonly owned copending applications of Yilmaz and Peters et al. Once a stack is inserted into the receptacle, the conveyor is withdrawn from the space between the bottom sheet of the stack and the bottom wall of the receptacle, the fourth side wall is pivoted to its upright position, and the top of the thus filled and completely assembled receptacle is provided with a prefabricated cover or lid. Each stack can constitute a discrete or single stack (e.g., a ream) of paper sheets or a group of two or more stacks each of which may but need not be provided with an envelope.
A drawback of heretofore known apparatus of the just outlined character is that the speed at which the stacks are transported and/or otherwise manipulated prior to and during introduction into receptacles cannot be increased at will because the sheets or layers of a stack are likely to be shifted relative to each other as soon as the speed is increased above a certain value and/or in response to abrupt stoppage or acceleration of the stack. Furthermore, heretofore known devices for ensuring proper registry of sheets in a stack and/or proper orientation of stacks relative to the transporting means therefor are rather bulky, complex expensive and prone to malfunction. Moreover, the stacks which are already inserted into the corresponding receptacles, such as the aforediscussed cardboard cartons or the like, are likely to follow at least some movements of the conveyor during extraction or retraction of the conveyor from a freshly filled receptacle with attendant minor or pronounced misorientation of the stack so that the fourth side wall of the receptacle cannot be moved to its upright position and/or the receptacle cannot be provided with a cover or lid.